This invention relates in general to subsea well systems, and particularly to a flowline jumper extending from a subsea well to another subsea component which may be in the form of a manifold, flowline or daisy chain to another well.
One oil and gas production technique for offshore wells utilizes subsea Christmas trees. The tree locates on top of the wellhead housing and contains valves for controlling the production. The tree also normally will have a choke and may have various monitors and flow measuring devices. The tree has a production outlet that typically connects to another subsea component, such as a manifold, that may be some distance away, such as 50 meters to several kilometers. A flowline jumper connects the subsea tree to the other component.
The flowline jumpers between the various components on the sea floor are typically rigid steel pipes that are laid horizontally on the sea floor. Prior to installation of the jumpers, the distances between the components are measured or calculated. Then pipes are fabricated to the desired length and provided with couplings on the ends for connecting between two components.
If the measurements are not precisely made or the components moved from originally planned locations, new jumpers may need to be fabricated. The distance and the orientation between the various subsea components must be known in advance before the flowline jumpers can be fabricated because the lengths will be critical. Also, after installation, if one of the components needs to be retrieved or moved, it is a time-consuming task to disconnect the flowline jumper from the component.
In this invention, a flowline jumper is provided that has a length greater than the distance between the two components that it is intended to connect. The flowline jumper has first and second connectors on opposite ends that are connected to the two components. At least a portion of the flowline jumper is buoyant and sufficiently flexible to cause that portion of the flowline to assume an arcuate configuration located in a vertical plane. The excess length and arcuate configuration reduces the need for the length of the flowline jumper to be precise. Also, the orientation may be changed more readily.
Preferably, at least one of the connectors on the flowline jumper is vertical so that it will stab vertically into a mating receptacle on one of the subsea components. Both of the connectors may be vertical. Alternately, one of the connectors may be horizontal. If so, this results in a portion of the flowline jumper being horizontally oriented and the other portion being arcuate.
The production tree is mounted to a wellhead housing. In one embodiment, the wellhead housing has a ring that is mounted to its exterior, the ring being selectively rotatable relative to the wellhead housing. An arm extends from the ring, the arm having a vertical socket. With the assistance of a remote operated vehicle (ROV), the ring can be rotated to position the socket at various orientations. The flowline from the tree aligns with the arm. The flowline jumper has a connector with a mandrel that stabs into the socket to align the flowline connector with the tree coupling. Preferably, the connector and the mandrel are hinged for ease in installation.